The goal of this project is to understand how the motors which power fast axonal transport interact with microtubules to promote movement. A second goal arising during the previous year has been to investigate how the motor proteins interact with vesicular organelles to generate movement in either the anterograde or retrograde directions. We are analyzing microtubule gliding and bead movement along microtubules powered by kinesin and by the recently purified retrograde motor which turns out to be dynein. In addition to analyzing the movement of artificial substrates coated with the motor proteins, the motion of organelles purified from axoplasm is being investigated. This project involves analyzing microtubule based motility by video microscopy, using a digital processor to generate images with sufficient contrast to visualize single microtubules and to acquire and analyze motion as a function of manipulations of the chemical environment. A procedure for tracking at 10 angstrom resolution the motion of organelles or beads moving on microtubules has been successfully implemented. This new technique is providing information about the molecular mechanical events that drive the movement of organelles along microtubules.